Abstract:

A thermoelectric conversion module which has a P-type thermoelectric
conversion material and an N-type thermoelectric conversion material
electrically connected to each other. The P-type thermoelectric
conversion material and the N-type thermoelectric conversion material are
joined with insulating material particles (ceramic spherical particles)
interposed therebetween, so as not to be electrically connected to each
other. The insulating material particles are joined to the P-type
thermoelectric conversion material with a first adhesive material
interposed therebetween and to the N-type thermoelectric conversion
material with a second adhesive material interposed therebetween, and the
P-type thermoelectric conversion material and the N-type thermoelectric
conversion material are electrically connected to each other in a region
other than the region in which the thermoelectric conversion materials
are joined with the first and second adhesive material and the insulating
material particles interposed therebetween.

Claims:

1. A thermoelectric conversion module comprising: a P-type thermoelectric
conversion material; an N-type thermoelectric conversion material; and
insulating material particles joined to the P-type thermoelectric
conversion material with a first adhesive material interposed
therebetween and joined to the N-type thermoelectric conversion material
with a second adhesive material interposed therebetween, wherein the
P-type thermoelectric conversion material and the N-type thermoelectric
conversion material are electrically connected to each other in a region
other than a region in which the P-type and N-type thermoelectric
conversion materials are joined with the first adhesive material and the
second adhesive material and the insulating material particles interposed
therebetween.

2. The thermoelectric conversion module according to claim 1, wherein the
insulating material particles have a 3CV value of 20% or less indicating
a variation in particle diameter.

3. The thermoelectric conversion module according to claim 2, wherein the
insulating material particles are ceramic spherical particles which have
an average particle diameter of 0.05 to 0.6 mm.

4. The thermoelectric conversion module according to claim 1, wherein the
insulating material particles have an average particle diameter of 0.05
to 0.6 mm.

6. The thermoelectric conversion module according to claim 1, wherein the
first and second adhesive materials are glass based materials.

7. The thermoelectric conversion module according to claim 1, wherein the
first and second adhesive materials are not in contact with each other.

8. The thermoelectric conversion module according to claim 1, wherein the
P-type thermoelectric conversion material and the N-type thermoelectric
conversion material are electrically connected in series.

9. A method for manufacturing a thermoelectric conversion module wherein
a P-type thermoelectric conversion material and an N-type thermoelectric
conversion material are joined with insulating material particles
interposed therebetween, the insulating material particles are joined to
the P-type thermoelectric conversion material with a first adhesive
material interposed therebetween and to the N-type thermoelectric
conversion material with a second adhesive material interposed
therebetween, and the P-type thermoelectric conversion material and the
N-type thermoelectric conversion material are electrically connected to
each other in a region other than a region in which the thermoelectric
conversion materials are joined with the first adhesive material and the
second adhesive material and the insulating material particles interposed
therebetween, the method comprising: preparing the P-type thermoelectric
conversion material and the N-type thermoelectric conversion material,
applying the first adhesive material to a first joint surface of the
P-type thermoelectric conversion material, the first joint surface to be
joined to the N-type thermoelectric conversion material; applying the
second adhesive material to a second joint surface of the N-type
thermoelectric conversion material, the second joint surface to be joined
to the P-type thermoelectric conversion material; providing at least one
of the first and second joint surfaces of the P-type thermoelectric
conversion material and the N-type thermoelectric conversion material
with the insulating material particles, the insulating material particles
having a particle diameter greater than a total thickness of the first
and second adhesive materials applied to the first and second joint
surfaces; and attaching the P-type thermoelectric conversion material and
the N-type thermoelectric conversion material to each other with the
insulating material particles and the first and second adhesive materials
interposed therebetween.

10. The method for manufacturing a thermoelectric conversion module
according to claim 9, wherein particles with a 3CV value of 20% or less
indicating a variation in particle diameter are used as the insulating
material particles.

11. The method for manufacturing a thermoelectric conversion module
according to claim 10, wherein ceramic spherical particles with an
average particle diameter of 0.05 to 0.6 mm are used as the insulating
material particles.

12. The method for manufacturing a thermoelectric conversion module
according to claim 9, wherein the insulating material particles have an
average particle diameter of 0.05 to 0.6 mm.

13. The method for manufacturing a thermoelectric conversion module
according to claim 9, wherein the insulating material particles are
spherical zirconium oxide beads.

14. The method for manufacturing a thermoelectric conversion module
according to claim 9, wherein glass based materials are used as the first
and second adhesive materials.

15. The method for manufacturing a thermoelectric conversion module
according to claim 9, the method further comprising: arranging the P-type
thermoelectric conversion material and the N-type thermoelectric
conversion material such that the first and second adhesive materials are
not in contact with each other.

16. The method for manufacturing a thermoelectric conversion module
according to claim 9, the method further comprising: electrically
connecting the P-type thermoelectric conversion material to the N-type
thermoelectric conversion material.

17. The method for manufacturing a thermoelectric conversion module
according to claim 16, the method further comprising: electrically
connecting the P-type thermoelectric conversion material to the N-type
thermoelectric conversion material in series.

Description:

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] The present application is a continuation of International
Application No. PCT/JP2009/061686, filed Jun. 26, 2009, which claims
priority to Japanese Patent Application No. JP2008-173694, filed Jul. 2,
2008, the entire contents of each of these applications being
incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

[0002] The present invention relates to a thermoelectric conversion module
and a method for manufacturing the thermoelectric conversion module, and
more particularly, relates to a thermoelectric conversion module which
has a P-type thermoelectric conversion material and an N-type
thermoelectric conversion material joined with an insulating material
interposed therebetween and has an increased occupancy of the
thermoelectric conversion materials per area, and a method for
manufacturing the thermoelectric conversion module.

BACKGROUND OF THE INVENTION

[0003] In recent years, for the purpose of preventing global warming, the
reduction of carbon dioxide has come to be a critical issue, and
attention has been focused on thermoelectric conversion elements capable
of converting heat directly into electricity as one of effective
techniques for waste heat utilization.

[0004] Furthermore, as a conventional thermoelectric conversion element,
for example, a thermoelectric conversion element 50 is known which has a
structure including a P-type thermoelectric conversion material 51, an
N-type thermoelectric conversion material 52, a lower temperature
electrode 56, and a higher temperature electrode 58, as shown in FIG. 8.

[0005] In this thermoelectric conversion element 50, the two types of
thermoelectric conversion materials 51, 52 are materials for energy
conversion between heat and electricity, which are connected to lower
temperature electrodes 56 at lower temperature joints 53b as their
respective lower temperature end surfaces. In addition, the
thermoelectric conversion materials 51, 52 are connected to each other at
higher temperature joints 53a as their respective higher temperature end
surfaces, through the higher temperature electrode 58.

[0006] Then, in this thermoelectric conversion element 50, when a
difference in temperature is provided between the higher temperature
joints 53a and the lower temperature joints 53b, an electromotive force
is produced as a result of the Seebeck effect, and electric power is then
extracted.

[0007] In the meanwhile, the electric generating capacity of a
thermoelectric conversion element is determined by thermoelectric
conversion characteristics of the material and the difference in
temperature provided to the element, and also affected significantly by
the occupancy (the ratio of the area occupied by the thermoelectric
conversion material section in a plane perpendicular to the direction of
the difference in temperature caused in the thermoelectric conversion
element) of the thermoelectric conversion material, and the increased
occupancy of the thermoelectric conversion material allows the electric
generating capacity of the thermoelectric conversion element per unit
area to be increased.

[0008] However, in the case of the structure of a conventional example as
in the thermoelectric conversion element 50, there is a limit to the
increase in the occupancy of the thermoelectric conversion materials,
because a void layer for insulation is provided between the two types of
thermoelectric conversion materials 51, 52.

[0009] Thus, for example, as shown in FIGS. 9(a) and (b), a thermoelectric
conversion module has been proposed in which a P-type thermoelectric
conversion material 51 and an N-type thermoelectric conversion material
52 are joined with an insulating layer 61 interposed therebetween, and
the P-type thermoelectric conversion material 51 and the N-type
thermoelectric conversion material 52 are electrically connected through
an electrode 62 on the sides of the top and bottom surfaces (see Patent
Document 1).

[0010] Specifically, as shown in FIG. 9(b), the P-type thermoelectric
conversion material 51 and the N-type thermoelectric conversion material
52 are joined at sides (joint surfaces) thereof with the insulating layer
61 interposed therebetween, while the side of the top surface has a
carbon electrode 71 provided thereon, with a nickel based wax 72 and a
molybdenum electrode 73 provided sequentially on the carbon electrode 71,
in such a way that the P-type thermoelectric conversion material 51 and
the N-type thermoelectric conversion material 52 are electrically
connected to each other by the electrode 62 composed of the carbon
electrode 71, the nickel based wax 72, and the molybdenum electrode 73.

[0011] Furthermore, as the material constituting the insulating layer 61,
an electrically insulating material is used which has ceramic particles
dispersed in a glass matrix.

[0012] The thus configured thermoelectric conversion module has the P-type
thermoelectric conversion material 51 and the N-type thermoelectric
conversion material 52 joined with the insulating layer 61 interposed
therebetween, in such a way that there is no space between the both
thermoelectric conversion materials, thus has an increased occupancy of
the thermoelectric conversion materials, and can improve the electric
generating capacity per unit area. [0013] Patent Document 1: Japanese
Patent Application Laid-Open No. 2000-286467

[0014] However, in the case of joining the P-type thermoelectric
conversion material 51 and the N-type thermoelectric conversion material
52 with the use of the electrically insulating material of the ceramic
particles dispersed in the glass matrix as in the case of the
conventional thermoelectric conversion module, when the glass component
constituting the glass matrix has conductivity due to impurities, or
comes to have conductivity by diffusion of the constituents of the
thermoelectric conversion materials in a firing step, there is a problem
of insufficient insulation between the P-type thermoelectric conversion
material and the N-type thermoelectric conversion material, thereby
leading to degradation of characteristics.

SUMMARY OF THE INVENTION

[0015] The present invention has been achieved in view of the actual
circumstance described above, and an object of the present invention is
to provide a thermoelectric conversion module which has a structure of a
P-type thermoelectric conversion material and an N-type thermoelectric
conversion material joined at predetermined joint surfaces thereof, which
makes it possible to ensure that the joint surfaces of the P-type
thermoelectric conversion material and the N-type thermoelectric
conversion material are insulated from each other and has an increased
occupancy of the thermoelectric conversion materials with high
reliability, and a method for manufacturing the thermoelectric conversion
module.

[0016] In order to solve the problem described above, the thermoelectric
conversion module of the present invention is characterized in that a
thermoelectric conversion module which has a P-type thermoelectric
conversion material and an N-type thermoelectric conversion material
electrically connected to each other. The P-type thermoelectric
conversion material and the N-type thermoelectric conversion material are
joined with insulating material particles interposed between joint
surfaces of the both thermoelectric conversion materials, so as not to be
electrically connected to each other. The insulating material particles
are joined to the P-type thermoelectric conversion material with a first
adhesive material interposed therebetween and to the N-type
thermoelectric conversion material with a second adhesive material
interposed therebetween. The P-type thermoelectric conversion material
and the N-type thermoelectric conversion material are electrically
connected to each other in a region other than the region in which the
thermoelectric conversion materials are joined with the first adhesive
material and the second adhesive material and the insulating material
particles interposed therebetween.

[0017] Preferably, the insulating material particles have a 3CV value of
20% or less indicating a variation in particle diameter.

[0018] Preferably, the insulating material particles are ceramic spherical
particles which have an average particle diameter of 0.05 to 0.6 mm.

[0019] In addition, preferably, the first and second adhesive materials
are glass based materials.

[0020] Furthermore, the method for manufacturing a thermoelectric
conversion module of the present invention is characterized in that it is
a method for manufacturing a thermoelectric conversion module wherein a
P-type thermoelectric conversion material and an N-type thermoelectric
conversion material are joined with insulating material particles
interposed therebetween, the insulating material particles are joined to
the P-type thermoelectric conversion material with a first adhesive
material interposed therebetween and to the N-type thermoelectric
conversion material with a second adhesive material interposed
therebetween, and the P-type thermoelectric conversion material and the
N-type thermoelectric conversion material are electrically connected to
each other in a region other than the region in which the thermoelectric
conversion materials are joined with the first adhesive material and the
second adhesive material and the insulating material particles interposed
therebetween. The method includes the steps of: preparing the P-type
thermoelectric conversion material and the N-type thermoelectric
conversion material; applying the first adhesive material to a joint
surface of the P-type thermoelectric conversion material, the joint
surface to be joined to the N-type thermoelectric conversion material
with the insulating material particles interposed therebetween, and
applying the second adhesive material to a joint surface of the N-type
thermoelectric conversion material, the joint surface to be joined to the
P-type thermoelectric conversion material with the insulating material
particles interposed therebetween; providing at least one of the joint
surfaces of the P-type thermoelectric conversion material and the N-type
thermoelectric conversion material, the at least one joint surface with
the first or second adhesive material applied thereto, with the
insulating material particles with a particle diameter greater than the
total thickness of the first and second adhesive materials applied to the
pair of joint surfaces, to allow the first and second adhesive materials
to hold the insulating material particles; and attaching the P-type
thermoelectric conversion material and the N-type thermoelectric
conversion material to each other with the insulating material particles
and the first and second adhesive materials interposed therebetween.

[0021] Preferably, particles with a 3CV value of 20% or less indicating a
variation in particle diameter are used as the insulating material
particles.

[0022] Preferably, ceramic spherical particles with an average particle
diameter of 0.05 to 0.6 mm are used as the insulating material particles.

[0023] Preferably, glass based materials are used as the first and second
adhesive materials.

[0024] In the thermoelectric conversion module according to the present
invention, the P-type thermoelectric conversion material and the N-type
thermoelectric conversion material are joined with the insulating
material particles interposed therebetween, so as not to be electrically
connected, and the insulating material particles are joined to the P-type
thermoelectric conversion material with the first adhesive material
interposed therebetween and joined to the N-type thermoelectric
conversion material with the second adhesive material interposed
therebetween. Thus, even when the first and second adhesive materials
composed of, for example, a glass component have conductivity due to
impurities, or come to have conductivity by diffusion of the constituents
of the thermoelectric conversion materials in a firing step, the
thermoelectric conversion module makes it possible to ensure that the
insulation is kept between the P-type thermoelectric conversion material
and the N-type thermoelectric conversion material, and thus provide a
thermoelectric conversion module which has an increased occupancy of the
thermoelectric conversion materials with high reliability.

[0025] It is to be noted that the first adhesive material and the second
adhesive material may be the same material, or may be different materials
in the present invention.

[0026] In addition, when particles with a 3CV value of 20% or less
indicating a variation in particle diameter are used as the insulating
material particles, the thermoelectric conversion module with the
substantially parallel joint surfaces of the P-type thermoelectric
conversion material 1 and the N-type thermoelectric conversion material 2
allows the joint surfaces to be opposed at approximately the same
distance in any position, as schematically shown in FIG. 2, and this
configuration thus makes it possible to arrange a number of P-type
thermoelectric conversion materials 1 and N-type thermoelectric
conversion materials 2 in an aligned manner, and thus provide a
thermoelectric conversion module which has an increased occupancy of the
thermoelectric conversion materials with high reliability.

[0027] The use of the ceramic spherical particles with an average particle
diameter of 0.05 to 0.6 mm as the insulating material particles makes it
possible to ensure that the joint surfaces of the P-type thermoelectric
conversion material and the N-type thermoelectric conversion material are
kept substantially parallel to each other, and thus provide a
thermoelectric conversion module which has an increased occupancy of the
thermoelectric conversion materials with high reliability.

[0028] In addition, the use of the glass based materials as the first and
second adhesive materials makes it possible to ensure that a
thermoelectric conversion module is provided which has a structure in
which the P-type thermoelectric conversion material and the N-type
thermoelectric conversion material are joined with the first and second
adhesive materials and the insulating material particles interposed
therebetween.

[0029] Furthermore, in the method for manufacturing a thermoelectric
conversion module according to the present invention, the adhesive
materials (the first and second adhesive materials) are applied to the
pair of joint surfaces of the P-type thermoelectric conversion material
and the N-type thermoelectric conversion material, which are to be joined
to each other with the insulating material particles interposed
therebetween, at least one of the pair of joint surfaces with the
adhesive materials applied thereto is provided with the insulating
material particles with a particle diameter greater than the total
thickness of the adhesive materials applied to the pair of joint
surfaces, to allow the adhesive materials to hold the insulating material
particles, and the P-type thermoelectric conversion material and the
N-type thermoelectric conversion material are then attached to each other
with the insulating material particles and the adhesive materials
interposed therebetween. Thus, the method makes it possible to ensure
that the insulation is kept between the P-type thermoelectric conversion
material and the N-type thermoelectric conversion material, and to
efficiently manufacture a thermoelectric conversion module which has an
increased occupancy of the thermoelectric conversion materials with high
reliability.

[0030] The use of particles with a 3CV value of 20% or less indicating a
variation in particle diameter as the insulating material particles
allows the joint surfaces of the P-type thermoelectric conversion
material 1 and the N-type thermoelectric conversion material 2 to be kept
substantially parallel to each other, and thus allows a thermoelectric
conversion module which has an increased occupancy of the thermoelectric
conversion materials with high reliability to be manufactured
efficiently.

[0031] The use of the ceramic spherical particles with an average particle
diameter of 0.05 to 0.6 mm as the insulating material particles makes it
possible to ensure that the joint surfaces of the P-type thermoelectric
conversion material and the N-type thermoelectric conversion material are
kept substantially parallel to each other, and thus manufacture, with
more certainty, a thermoelectric conversion module which has an increased
occupancy of the thermoelectric conversion materials with high
reliability.

[0032] In addition, the use of the glass based materials as the first and
second adhesive materials makes it possible to manufacture a
thermoelectric conversion module efficiently even with certainty, which
has a structure in which the P-type thermoelectric conversion material
and the N-type thermoelectric conversion material are joined with the
first and second adhesive materials and the insulating material particles
interposed therebetween.

BRIEF EXPLANATION OF THE DRAWINGS

[0033]FIG. 1 is a plan view illustrating a thermoelectric conversion
module according to an example of the present invention.

[0034] FIG. 2 is a cross-sectional elevational view illustrating the
structure of a main section of the thermoelectric conversion module of
FIG. 1.

[0035]FIG. 3 is a diagram illustrating a step of a method for
manufacturing a thermoelectric conversion module according to the example
of the present invention.

[0036]FIG. 4 is a diagram illustrating another step of the method for
manufacturing a thermoelectric conversion module according to the example
of the present invention.

[0037]FIG. 5 is a diagram illustrating ceramic spherical particles
(spherical zirconium oxide beads) arranged on glass pastes applied to
sides of thermoelectric elements in a step for manufacturing a
thermoelectric conversion module according to the example of the present
invention.

[0038]FIG. 6 is a diagram illustrating the respective thermoelectric
elements joined in a step for manufacturing a thermoelectric conversion
module according to the example of the present invention.

[0039] FIG. 7 is a diagram illustrating the respective thermoelectric
elements connected in series through electrodes in a step for
manufacturing a thermoelectric conversion module according to the example
of the present invention.

[0041] FIGS. 9(a) and 9(b) are diagrams illustrating another conventional
thermoelectric conversion module, in which FIG. 9(a) is a plan view, and
FIG. 9(b) is a diagram illustrating an enlarged main section.

[0048] Features of the present invention will be described in more detail
below with reference to an example of the present invention.

Example

[0049]FIG. 1 is a plan view schematically illustrating the structure of a
thermoelectric conversion module according to an example of the present
invention, and FIG. 2 is a cross-sectional elevational view illustrating
an enlarged main section.

[0050] In this thermoelectric conversion module, as shown in FIGS. 1 and
2, thermoelectric elements (a P-type thermoelectric conversion material 1
and an N-type thermoelectric conversion material 2) are joined so as not
to be electrically connected to each other, with ceramic spherical
particles (insulating material particles) 11 of, for example, 0.05 to 0.6
mm in particle diameter interposed the thermoelectric elements, which
have a 3CV value of 20% or less indicating a variation in particle
diameter. It is to be noted that spherical zirconium oxide beads are used
as the ceramic spherical particles 11.

[0051] Furthermore, the ceramic spherical particles 11 are joined to the
P-type thermoelectric conversion material 1 with a glass based material
21 as a first adhesive material interposed therebetween, and joined to
the N-type thermoelectric conversion material 2 with a glass based
material 22 as a second adhesive material interposed therebetween, and
the glass based material 21 and the glass based material 22 are kept not
in contact with each other.

[0052] It is to be noted that the same glass based material is used as the
first glass based material 21 and the second glass based material 22 in
this example. However, it is also possible to use different types of
glass as the first and second glass based materials 21, 22.

[0053] In addition, electrodes 12 (see FIG. 2) (the electrodes are omitted
in FIG. 1) are provided in a region (on the top surface and bottom
surface in the case of the thermoelectric conversion module according to
this example) other than the region in which the thermoelectric
conversion materials are joined with the glass based materials 21, 22 and
the ceramic spherical particles 11 interposed therebetween, in such a way
that the P-type thermoelectric conversion material 1 and the N-type
thermoelectric conversion material 2 are electrically connected in
series. In addition, the thermoelectric conversion module according to
this example is formed from 36 thermoelectric elements in total, in a
matrix of 6×6.

[0054] However, the thermoelectric conversion module according to the
present invention is not to be considered limited to this example, in
terms of how to provide the P-type thermoelectric conversion material 1
and the N-type thermoelectric conversion material 2 and the number of
P-type thermoelectric conversion materials 1 and N-type thermoelectric
conversion materials 2 used.

[0055] In addition, the electrode for connecting each pair of P-type
thermoelectric conversion material 1 and N-type thermoelectric conversion
material 2 in series is not particularly limited in terms of how to
provide the electrode and how to extract the electrode, which can be
determined in consideration of the size and shape of each thermoelectric
element, the number of thermoelectric elements used, etc.

[0056] In the thermoelectric conversion module according to this example,
as described above, the P-type thermoelectric conversion material 1 and
the N-type thermoelectric conversion material 2 are joined so as not to
be electrically connected, with the ceramic spherical particles 11 as
insulating material particles interposed therebetween, the ceramic
spherical particles 11 are joined to the P-type thermoelectric conversion
material 1 with the glass based material 21 as a first adhesive material
interposed therebetween and joined to the N-type thermoelectric
conversion material 2 with the glass based material 22 as a second
adhesive material interposed therebetween, and the glass based material
21 as a second adhesive material and the glass based material 22 as a
second adhesive material are kept not in contact with each other. Thus,
even when the glass based materials 21, 22 have conductivity due to
impurities, or come to have conductivity by diffusion of the constituents
of the thermoelectric conversion materials in a firing step, the
thermoelectric conversion module makes it possible to ensure that the
insulation is kept between the P-type thermoelectric conversion material
1 and the N-type thermoelectric conversion material 2, thereby providing
a thermoelectric conversion module with high reliability.

[0057] In addition, since the P-type thermoelectric conversion material 1
and the N-type thermoelectric conversion material 2 are joined with the
ceramic spherical particles 11 which have a 3CV value of 20% or less in
terms of particle diameter and thus a small variation in particle
diameter, the thermoelectric conversion module with the joint surfaces of
the P-type thermoelectric conversion material 1 and the N-type
thermoelectric conversion material 2 substantially parallel to each other
allows the joint surfaces to be opposed at approximately the same
distance in any position, as shown in FIGS. 1 and 2. Therefore, this
configuration makes it possible to arrange the P-type thermoelectric
conversion material 1 and the N-type thermoelectric conversion material 2
tightly while ensuring that the joint surfaces of the P-type
thermoelectric conversion material 1 and the N-type thermoelectric
conversion material 2 are prevented from coming into direct contact with
each other or the glass based materials 21, 22 applied to the joint
surfaces are prevented from coming into contact with each other, and thus
provide a thermoelectric conversion module which has an increased
occupancy of the thermoelectric conversion materials with high
reliability.

[0058] Further, since the thermoelectric conversion module with the joint
surfaces substantially parallel to each other allows the joint surfaces
to be opposed at approximately the same distance in any position, and
this configuration makes it possible to arrange thermoelectric elements
in an aligned manner with a high degree of accuracy in the case of
joining a number of P-type thermoelectric conversion materials 1 and
N-type thermoelectric conversion materials 2 with the insulating material
particles 11 interposed therebetween, thereby providing a thermoelectric
conversion module which has an increased occupancy of the thermoelectric
conversion materials with high reliability.

[0059] Next, a method for manufacturing the thermoelectric conversion
module according to this example will be described.

[0060] As raw material powders, La2O3, Nd2O3,
CeO2, SrCO3, and CuO were prepared, and weighed so as to
provide predetermined compositions of (La1.98Sr0.02)CuO4
as the P-type thermoelectric conversion material and of
(Nd1.98Ce0.02)CuO4 as the N-type thermoelectric conversion
material.

[0061] While the oxides were used as the raw material powders for La, Nd,
Ce, and Cu raw materials whereas the carbonate was used as the raw
material powder for a Sr raw material in this example, the starting raw
materials are not to be considered limited to the oxides and carbonate as
described above, and it is also possible to use other inorganic materials
such as hydroxides and organo-metallic compounds such as acetylacetonate
complexes.

[0062] The raw material powders weighed for each composition were ground
and mixed in a wet ball mill using pure water as a solvent. The slurry
containing the raw material powders was subjected to evaporation to
obtain a mixed powder.

[0063] Then, the mixed powder obtained was subjected to a heat treatment
at 900° C. for 8 hours in an air atmosphere to produce the
intended oxide powder for the thermoelectric conversion material. It is
to be noted that an unreacted portion may remain in this case.

[0064] The oxide powders for each thermoelectric conversion material,
obtained by carrying out this heat treatment, were mixed with an organic
binder at a ratio of 5 weight % to each composition powder, and ground
and mixed in a wet ball mill using pure water as a solvent.

[0065] After sufficiently drying the respective composition powers mixed
with the organic binder, a uniaxial pressing machine was used to produce
compacts of the dried composition powders at a pressure 10 MPa.

[0066] The compacts were fired in an air atmosphere in the range of
1000° C. to 1100° C. for 2 hours to produce sintered bodies
of the compacts composed of the oxide powders for each thermoelectric
conversion material.

[0067] It is to be noted that the firing temperature in this case varies
depending on the compositions of the oxide powders for each
thermoelectric conversion material.

[0068] Typically, the conditions are set to provide a relative density of
80% or more (preferably 90% or more).

[0069] The sintered bodies were clipped with the use of a dicing saw into
a size of 5 mm×5 mm×5 mm to obtain thermoelectric elements
(P-type thermoelectric conversion materials 1 and N-type thermoelectric
conversion materials 2) as shown in FIG. 3.

[0070] Then, as shown in FIG. 4, glass pastes (baked first and second
adhesive materials (glass based materials)) 21, 22 were applied to four
sides of the thermoelectric elements clipped in the predetermined size,
which were not intended to serve as conductive surfaces.

[0071] Then, before the glass pastes 21, 22 were dried, ceramic spherical
particles (spherical zirconium oxide beads) 11 with an average particle
size of 0.1 mm were arranged as insulating material particles so that one
or more ceramic spherical particles were distributed on the four corners
of the surfaces with the glass pastes 11 applied thereto, as shown in
FIG. 5.

[0072] Then, a surface of one thermoelectric element 1 with the ceramic
spherical particles (spherical zirconium oxide beads) 11 arranged thereon
was joined (provisionally joined) with a joint surface of other
thermoelectric element 2 with the glass paste 11 applied thereto. The
P-type thermoelectric conversion material 1 and the N-type thermoelectric
conversion material 2 formed a pair in this way, and this pair of
thermoelectric elements is provided so as to make an arrangement as shown
in FIG. 1, to provisionally join the respective thermoelectric elements,
and then dried in an oven at 150° C.

[0073] It is to be noted that while the types of the glass pastes 21, 22
are not particularly limited as long as the glass pastes 21, 22 can hold
the ceramic spherical particles 11, it is desirable to select the
compositions, concentrations, etc. of the glass pastes 21, 22
appropriately depending on the type, size, shape, etc. of the ceramic
spherical particles.

[0074] Then, the block of the thermoelectric elements (the P-type
thermoelectric conversion materials 1 and the N-type thermoelectric
conversion materials 2) joined in the way described above was introduced
into a tunnel furnace set to 900° C., in which the first and
second glass based materials were melted in the atmosphere to join
(couple) the thermoelectric elements with the ceramic spherical particles
and glass based materials interposed therebetween, as shown in FIG. 6.

[0075] Then, the surfaces of the block of the respective thermoelectric
elements joined, which are to serve as conductive surfaces, that is, the
top surface and bottom surface thereof were subjected to polishing.

[0076] Then, the elements were subjected to electrolytic Ni plating. It is
to be noted that since the sides of the elements were covered with the
glass for acting as resist, a Ni plating film was to be formed only on
the top and bottom surfaces of the respective thermoelectric elements.
Then, a Cu paste was applied by screen printing to the top and bottom
surfaces of the respective thermoelectric elements with the Ni plating
film formed thereon, in such a way that the thermoelectric elements (the
P-type thermoelectric conversion materials 1 and the N-type
thermoelectric conversion materials 2) were connected in series, copper
plates were placed thereon, and baking was then carried out at
860° C. in nitrogen to manufacture a thermoelectric module as
shown in FIG. 1 with the P-type thermoelectric conversion material 1 and
the N-type thermoelectric conversion material 2 connected in series by
the electrode 12 (the copper plate, see FIG. 2) (however, the electrode
for connecting the P-type thermoelectric conversion material 1 and N-type
thermoelectric conversion material 2 to each other is not illustrated in
FIG. 1).

[0077] The sample (thermoelectric conversion module) manufactured in the
way as described above was observed visually for the joining between the
thermoelectric element and the glass based material to find the joining
favorable.

[0078] In addition, the thermoelectric elements joined to each other with
the glass based materials and ceramic spherical particles interposed
therebetween were observed visually to find that the thermoelectric
elements were rigidly joined to each other without peeling, breaking, or
cracking found.

[0079] In addition, it has been confirmed that the resistance between the
thermoelectric elements is so high from 104 to 107Ω that
the insulating property between the thermoelectric elements is kept high
in the thermoelectric conversion module according to the example
described above.

[0080] Furthermore, in the thermoelectric conversion module according to
the example described above, it has been confirmed that the use of the
ceramic spherical particles with a 3CV value of 20% or less indicating a
variation in particle diameter results in the parallel joint surfaces of
the thermoelectric elements, and thus allows the thermoelectric elements
to be arranged in an aligned manner, thereby making it possible to ensure
an increased occupancy of the thermoelectric elements.

[0081] It is to be noted that while the case of using the spherical
zirconium oxide beads as the insulating material particles has been
described by way of example in the example described above, the type of
the insulating material particles is not particularly limited in the
present invention, it is possible to use insulating material particles
composed of various ceramic materials such as alumina and titania, and it
is also possible in some cases to use insulating material particles
composed of resin materials.

[0082] In addition, while the insulating glass was used as the adhesive
materials in the example described above, it is also possible to use
resin based materials instead of the insulating glass. Furthermore, since
the adhesive materials are kept not in contact with each other, it is
also possible in some cases to use, as the adhesive materials, materials
other than insulating materials.

[0083] It is to be noted that the present invention is further not to be
considered limited to the example described above in terms of other
aspects, various applications and modifications can be made within the
scope of the present invention, in terms of the compositions and raw
materials of the P-type thermoelectric conversion material and the N-type
thermoelectric conversion material, the specific structure of the
thermoelectric conversion module, the specific conditions (for example,
the size and the firing conditions, the number of thermoelectric
conversion elements constituting the thermoelectric conversion module,
etc.) at the time of manufacture, the types of the insulating material
particles and adhesive materials, etc.

[0084] As described above, the present invention makes it possible to
obtain a thermoelectric conversion module which has a structure of a
P-type thermoelectric conversion material and an N-type thermoelectric
conversion material joined with an insulating material interposed
therebetween, which makes it possible to ensure that the joint surfaces
of the P-type thermoelectric conversion material and the N-type
thermoelectric conversion material are insulated from each other and has
an increased occupancy of the thermoelectric conversion elements with
high reliability.

[0085] Accordingly, the present invention can be applied widely in
technical fields of thermoelectric conversion modules requiring an
increased occupancy of thermoelectric conversion elements and high
reliability.